1. Field of the Invention
The present invention relates to the field of truss structures. In particular, the present invention provides a greatly improved truss for a reflecting type telescope.
2. Description of the Related Art
In the construction and use of telescopes and, in particular, large telescopes, it is commonly found that deformation of the telescope frame occurs under various loads such as gravity, inertia, and wind. The size of many modern telescopes is such that the deformation caused by these forces results in defocusing the telescope.
In order to overcome the problems associated with these deformations, a common solution has been to use large, stiff structural members within the body of the telescope to control the deformation to within acceptable limits. This solution has the apparent drawbacks of the high weight and cost of the telescope and its associated hardware.
Telescopes have utilized a Serrurier Truss. The Serrurier Truss is a type of four-bar linkage which provides parallel movement of primary and secondary structures in the telescope. It, therefore, becomes necessary to "balance" the stiffness of the primary and secondary trusses so that gravity load deformations do not defocus the telescope, i.e., the body is designed such that when a force is applied, the amount of deflection occurring in the upper portion of the telescope is roughly equal to that occurring in the bottom portion of the telescope. The use of a Serrurier Truss in a telescope, however, does not maintain telescope focus under conditions created by wind, acceleration (from, for example, rotation of the telescope), and other similar types of loads. The sets of parallel trusses are not parallel and bear no relation to the focal point in a Serrurier Truss. Mt. Palomar is an example of a telescope using such a truss.